Medicine makes ever-increasing use of the systematic analysis of organic liquids, in particular in the field of preventive medicine and in hospitals. Certain of these analyses are of colorimetric nature, carried out with the aid of a reagent designed to give the liquid a certain coloration, and a light source of a specified wavelength. This wavelength is obtained in practice by using a filter placed between the actual light source and the liquid sample. Often, the same sample has to undergo several analyses. To this end, the sample is divided between several test tubes each containing a specific reagent, a light beam of a predetermined wavelength is directed through each test tube, and the beams emerging from said test tubes are measured by a photometer.
Automatic equipment already exists for successively feeding the substances to be analyzed to a colorimetric analysis station, but this equipment is able to carry out only one type of analysis at a time. Consequently, the samples have to be grouped for each type of analysis. In the case of a series of samples each of which is divided into fractions to be subjected to a cycle of colorimetric analysis,the fractions of these samples which have to undergo the same type of analysis are grouped so that the organic liquid originating from the same subject is divided among as many groups as there are analyses in the cycle. This practice gives rise to serious identification problems, and constitutes a considerable source of error which is completely unacceptable in view of its gravity.